Central authorization systems are known for authorizing users of a personal authentication device, such as a smart card, to have access to a building or to withdraw money from a bank, for example. Generally, the readers associated with a central authorization system include a processor and a memory for verifying whether the user of the personal authentication device is authorized to have access to the system.
However, the application of smart readers is relatively costly. On the other hand, reader systems are known including a limited number of individual readers, e.g. four readers, that are connected to a control unit. The control unit includes a processor and a memory for performing the verifying process. The control unit is connected to a central authorization system.
It is noted that American patent publications US 2007/0200665 and US 2006/0170533 each disclose an access control system including a central authorization system that is arranged for checking telephone data with a pre-loaded list of authorized telephones.
Such closed system are less flexible for application of personal authentication devices that are unknown to the central authorization system.